Implantable medical devices are used to deliver neurostimulation therapy to patients to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, incontinence, or gastroparesis. Typically, implantable medical devices deliver neurostimulation therapy in the form of electrical pulses via leads that include electrodes. To treat the above-identified symptoms or conditions, for example, the electrodes may be located proximate to the spinal cord, pelvic nerves, or stomach, or within the brain of a patient. The electrodes carried on one or more leads that are implanted within a patient may be referred to as an electrode set or array.
A clinician may select values for a number of programmable parameters in order to define the neurostimulation therapy to be delivered to a patient. For example, the clinician may select an amplitude, which may be a current or voltage amplitude, and pulse width for a stimulation waveform to be delivered to the patient, as well as a rate at which the pulses are to be delivered to the patient. The clinician may also select as parameters particular electrodes within an electrode set to be used to deliver the pulses, e.g., a combination of electrodes from the electrode set. A combination of electrodes may be defined by the polarities, e.g., positive, negative, or off (high impedance), of each of the electrodes within the electrode set. A group of parameter values may be referred to as a program in the sense that they drive the neurostimulation therapy to be delivered to the patient.
The process of selecting values for the parameters that provide adequate results can be time consuming, and, as a portion of the overall parameter selection process, the process of selecting combinations of electrodes can be particularly time-consuming and tedious. The clinician may need to test all possible combinations of electrodes within the set implanted in the patient, or a significant portion thereof, in order to identify one or more adequate combinations of electrodes. In some cases, the clinician may test combinations by manually specifying each combination to test based on intuition or some idiosyncratic methodology, and recording notes on the efficacy and side effects of each combination after delivery of stimulation via that combination. In this manner, the clinician is able to later compare and select from the tested combinations. As an example illustrating the magnitude of such a task, implantable medical devices commonly deliver spinal cord stimulation therapy (SCS) to a patient via two leads that include eight electrodes per lead and provide well over one million potential electrode combinations.